I don't know dude.
No one's got the ability to deploy and sustain any force an ocean away that could ever get close to challenging the US.
Even if they could get the defenses down, and luanch a few missiles etc. they couldn't land enough of anything to make a real difference.

How did I come up with those dates? Simple, China would need to build up a Navy and Russia would need to rebuild and refurbish their existing Navy, and Britain, well they can not dominate the world like they used to because they lost their colonies, so I just went back to when they were at the height of their power IMO, if they truly tried to retake America they most likely would have succeeded.

BTW, can anybody tell me the strategic importance of capturing those lands in gray?

http://img158.exs.cx/img158/8733/usoutline1cl.jpg

Establish Underground Military installations? Airbases? Anything you can think of.

Question, NORAD have been claimed to be located in where?

There are many reasons for wanting to hold the grey areas you have marked on the map. It completely separates the country, severing population centers, limiting the ability for a military response.



Ben

Or to create a DMZ/buffer zone. As Kane have said, you can do many things with that much land at your disposal.

idk about TX, the rednecks might just pull out their shotguns

Don't forget about how to fend off a pre-emptive strike by the US. Or an immediate retaliatory strike by Boomers, silos, and heavy bombers as well as stealth bombers. I think with good information gathering it may be possible to neutralize some of these but the subs would be a challenge.
The only successful invasion would be when the nuclear arsenal was either depleted or knocked out somehow. By then, if anything was left alive that didn't have radiation poisoning or burns, a ground force would have to funnel down through Canada and Alaska which is the weakest defended front. That's not a cut at Canada, it's just that the Southern border is so heavily defended. I would try a front from the North and try to cover from the East coast to the West coast with Naval and Airborne forces. When the Southwestern defense is pulled to the fronts, then another assault could begin from that direction. The Coastal assaults would be suicide.

Well I see nobody mentioned anything about the bread basket of America, the plains states produce most of the food for the whole country, if those fall the rest of the country will be hard pressed to try and find enough food to feed the soldiers and the people./